Belonolaimus Longicaudatus Host Status and Pathogenicity on Sweetpotato.

Sting nematode is acutely damaging to a wide range of crops and is relatively common in sandy soils in the southeastern United States. Sweetpotato is an important crop in this region, and its production may be expanding to localities where sting nematode is an important pest. Despite this, the relationship between sweetpotato and sting nematode is not well-defined. Therefore, the objectives of this study were to assess (1) the relative host status of sweetpotato for sting nematode and (2) damage potential of sting nematode on sweetpotato in repeated greenhouse experiments. A known sting nematode host (field corn), a known poor host (sunn hemp), and sweetpotato cultivars susceptible ('Beauregard') and resistant ('Covington') to southern root-knot nematode were challenged with sting nematode. In both trials, field corn supported greater final soil sting nematode abundances than sunn hemp or either sweetpotato cultivar. Based on the average reproductive factor, field corn was confirmed as a susceptible host, whereas sunn hemp and sweetpotato were poor hosts. Sting nematode did not impair the growth of any crop, suggesting greenhouse conditions were not conducive to damage since field corn sustains damage in field conditions. These results suggest that sunn hemp and sweetpotato could be useful rotation crops for managing sting nematode, but future work is needed to assess sting nematode pathogenicity on these crops under field conditions.

Anaerobic digestion to reduce biomass and remove arsenic from As-hyperaccumulator Pteris vittata.

The lack of efficient methods to treat As-rich biomass is a drawback for phytoremediation technology. In this study, we applied anaerobic digestion to reduce biomass and remove As from As-rich Pteris vittata biomass. P. vittata biomass including control (3.1 mg kg-1 As) and As-rich (2665 mg kg-1 As), together with positive and negative controls, was anaerobically digested at 35 °C for 35 d. Arsenic partitioning among gas, liquid and solid phases after anaerobic digestion was determined. Methane index potential assay was used to assess methane yields whereas liquid-displacement method was used to measure methane gas production. After 35 d, As partitioning in the liquid, solid and gas phases was 79, 30 and 1%, respectively. Besides, volatile solid was decreased from 91 to 12-17% total solid, while P. vittata biomass was decreased by 73-83%. Moreover, anaerobic digestion solubilized 76% As from P. vittata biomass, with 90% soluble As at 4.95 mg L-1 being recovered by As-Mg precipitation. Finally, methane production after 35 d was 197-212 LNCH4/kg volatile solid, showing slight As inhibition. Effective As removal from P. vittata biomass prior to disposal can improve the phytoremediation process.

Arsenic removal and biomass reduction of As-hyperaccumulator Pteris vittata: Coupling ethanol extraction with anaerobic digestion.

Improper disposal of arsenic-rich biomass and the lack of efficient methods to treat it may cause contamination in the environment. We developed an efficient method for arsenic (As) removal and biomass reduction of As-rich biomass of the As-hyperaccumulator Pteris vittata by coupling ethanol extraction with anaerobic digestion. This study assessed As partitioning among the three phases (gas, liquid and solid) after anaerobic digestion of P. vittata biomass. Biomass with and without As was first extracted with ethanol. Ethanol extraction removed ~93% As, with remaining As concentration at 197 mg kg-1. The extracted biomass was then digested at 35 °C under anaerobic conditions for 35 d. Arsenic in the digested biomass was reduced by 89%, with remaining As concentration at 60 mg kg-1. In addition, anaerobic digestion reduced the biomass by 64-71% and decreased the volatile solids content from 94 to 15-18%. Methane production was 145 and 160 LNCH4/kgVS after 35 d for As-rich and control biomass, respectively. As a final step, As concentration in anaerobic digestate supernatant was reduced to 0.26 mg L-1 by As-Mg precipitation. Overall, coupling ethanol extraction with anaerobic digestion decreased As concentration in P. vittata biomass from 2665 to 60 mg kg-1, or by 98%. At this level (<100 mg As kg-1), P. vittata biomass can be considered a safe material based on USEPA regulations. Effective As removal from P. vittata biomass prior to disposal improves the phytoremediation process and lowers biomass transport and landfill disposal costs.

Feed and fuel: the dual-purpose advantage of an industrial sweetpotato.

BACKGROUND: Sustainable agricultural systems must support nutritional requirements, meet the energy demands of a growing population, preserve environmental resources and mitigate climate change. The sweetpotato (Ipomoea batatas L.) is a high-yielding crop that requires minimal fertilization and irrigation, and the CX-1 industrial cultivar offers superior potential for feed and fuel. RESULTS: CX-1 had the highest agronomic fresh vine yield (51.5 t ha-1 ), averaged over two cropping seasons, compared with Hernandez (33.7) and Beauregard (21.8) varieties. CX-1 vines were more nutritional than the table varieties, specifically in regard to relative feed value (205), water-soluble carbohydrates (171 g kg-1 dry matter (DM)), total digestible nutrients (643 g kg-1 DM), metabolizable energy (10.2 MJ kg-1 DM) and organic matter digestibility. Their lower fiber and lignin concentrations contributed to their freshness and digestibility throughout maturity. Significantly higher iron concentrations make the CX-1 vines a valuable, low-fat iron supplement for animal feed. The CX-1 roots also showed the highest bioethanol potential (82.3 g ethanol kg-1 fresh root) compared to Hernandez (64.5) and Beauregard (48.1). CONCLUSION: The CX-1 industrial sweetpotato is an ideal dual-purpose crop for tropical/subtropical climates that can be utilized as a non-grain-based feedstock for bioethanol production while contributing a valuable, high-yielding nutritional supplement for animal feed. © 2016 Society of Chemical Industry.

Enhanced methane production from rice straw co-digested with anaerobic sludge from pulp and paper mill treatment process.

Rice straw is a widely available lignocellulosic waste with potential for energy recovery through anaerobic digestion. Lignin slows the hydrolysis phase, resulting in low methane recovery and long digestion periods. Although pretreatment is effective, it often requires high energy inputs or chemicals that are not feasible for farm-scale systems. This study investigates a unique co-digestion strategy to improve methane yields and reduce digestion times for farm-scale systems. By adding both piggery wastewater and paper mill sludge, specific methane yields in laboratory-scale digesters reached the theoretical value for rice straw (i.e. 330LNCH4/kgVS) over the 92-day period. Accelerated hydrolysis of the straw was directly related to the quantity of sludge added. The most stable digester, with sufficient buffering capacity and nutrients, contained equal parts of straw, wastewater and sludge. This approach is feasible for farm-scale applications since it requires no additional energy inputs or changes to existing infrastructure for dry systems.